This invention relates to wound dressings and, more particularly, to a transparent, flexible wound dressing product containing a hydrogel substance.
Secreting skin wounds, such as decubitus ulcers and open surgical wounds, have long presented a medical challenge in keeping such wounds sterile and relatively dry. The accumulation of wound exudate, such as blood, Pustulation, and other wound fluids, in wound crevices promotes growth of bacteria and crusted organisms which cause infection and delay the healing process. However, since it is often desirable to allow a wound to heal in a slightly "moist" or occlusive state as it is believed that this may accelerate healing, excess wound exudate must be removed. If excess wound exudate remains on a wound, a "blister" of exudate can form under the wound dressing which is not only unsightly, but also may cause the dressing to leak, thereby defeating the aim of sterility. However, existing methods of aspiration can lead to wound infection or can destroy sterility. Additionally, it is not desirable to remove all the exudate as that would result in a "dry" wound and hence a slower healing process.
One existing wound exudate absorption method is to apply a hydrogel composition to a wound. As disclosed in Mason, Jr. et al, U.S. Pat. No. 4,393,048, issued July 12, 1983, a currently existing hydrogel wound treatment composition dries to a powder form after it is introduced to an open, draining wound to absorb wound exudate. However, dry hydrogel deteriorates as the wound fluids are absorbed resulting in lumping and uneven application. Additionally, such deteriorated lumps are difficult to remove from a wound site without damaging new cell tissue at the wound site. Furthermore, the progress of wound healing cannot be determined without removing, at least partially, the wound dressing from the wound site.
Aqueous moisture absorbing materials, such as a hydrogel material with a polyethylene glycol liquid curing agent as disclosed in Spence, U.S. Pat. No. 4,226,232, issued Oct. 7, 1980, are easier to remove from the wound site, but cannot be sterilized by irradiation due to the formation of free radicals within the aqueous material. Another aqueous absorbing material used to absorb wound exudate, hydrophilic polymer, is disclosed in Rawlings et al, U.S. Pat. No. 4,657,006, issued Apr. 14, 1987. In the Rawlings et al reference, a wound dressing is described which comprises a hydrophilic polymer having moisture vapor permeability characteristics. One problem with the Rawlings et al wound dressing is that the wound exudate absorbed by the hydrophilic polymer hardens the polymer, allowing pockets to develop between the polymer and the wound, providing an excellent environment for bacteria proliferation.
Known aqueous moisture absorbing wound dressing systems have additional problems, in that the aqueous material is generally contained in the center portion of a wound dressing, with a bulky adhesive border, such as a foam border. Problems with such borders include decreased comfort, conformity and adhesion as well as the existence of a "lifting edge" that can catch on clothes or bed sheets, thereby exposing the wound to bacteria and infection. In addition, observation of the wound by medical personnel may require lifting the wound dressing thereby exposing the wound, again creating a situation where bacteria and infection can be introduced to the wound site.
An existing method of overcoming the problems associated with bulky wound dressings is disclosed in Potts, U.S. Pat. No. 3,526,224 issued Sep. 1, 1970. The Potts reference discloses a wound dressing comprised of an elastomeric polyurethane film which acts as a second skin during the wound healing process. One problem with the Potts wound dressing, however, is that the "second skin" requires surgery to remove it after the wound has healed. A method which overcomes the surgical removal requirement of the Potts wound dressing is disclosed in Melzanis, U.S. Pat. No. 3,543,750, issued Dec. 1, 1970. The Melzanis reference discloses a wound dressing having a low degree of adhesion which can be easily removed from a wound site after the wound has healed. However, the low degree of adhesion impairs the ability of the Melzanis wound dressing to adhere to a wound during the healing process.
It would be desirable to provide a wound dressing product which could be precut, sterilized, and readily available for application to a draining wound. It would also be desirable to provide a wound dressing containing an exudate absorbing composition which would not decay or harden as the exudate is absorbed. In addition, it would be desirable to provide a transparent wound dressing which would permit observation of the wound without removal of the wound dressing. Further, it would be desirable to provide a wound dressing which could be removed neatly and, more importantly, without adhering to the new cell tissue of the wound. Finally, it would be desirable to provide a wound dressing with improved conformity and adhesion which could be comfortably applied to any area on a body.